The present invention relates to fixation devices or anchors and tools and methods for emplacing same. The present invention, in particular, relates to medical anchors, e.g., suture anchors or prosthesis anchors. It further relates to a method and apparatus for emplacing an anchor in biological material, for example, bone. Even more particularly, the present invention relates to a medical anchor which can be inserted through a longitudinally extending borehole so that the anchor is initially substantially aligned with the borehole and then, via an emplacement tool, manipulated so that the anchor pivots in two axes to form an undercut in the borehole and is secured substantially perpendicularly to the longitudinal extent of the borehole. The present invention is particularly suitable for the emplacement of anchors adapted to repair ligaments, e.g., rotator cuff ligaments, anterior cruciate ligaments (ACL's) and other ligaments. The anchor is also suitable for prosthesis fixation.
In Applicant's co-pending U.S. patent application Ser. No. 08/470,988, filed Jun. 6, 1995, a medical anchor is disclosed which can be emplaced in a groove which extends substantially parallel to the surface of the bone. The anchor of that patent application is placed in the groove, and then rotated along an axis defined by the tool (and which axis is perpendicular to the extent of the groove) to form an undercut in the walls of the groove in the bone to secure the anchor. The anchor of that application is suitable for repairing rotator cuff injuries, for example.
Applicant is also aware of U.S. Pat. No. 5,203,787 to Noblitt et al., in which a suture anchor can be emplaced in bone. This anchor is inserted in a longitudinally extending hole and then is twisted into place by manipulation of the sutures so that the suture anchor pivots along an axis which is perpendicular to the longitudinal axis of the borehole.
U.S. Pat. No 5,569,302 to Johnson describes an apparatus and method for attaching an object to bone in which a special tool is provided to form a groove which extends both longitudinally parallel to the bone and distally into the bone and a special tool is utilized to form an undercut into which the anchor is fitted.
The various prior art devices suffer from a number of defects. In the above-described co-pending patent application, although a securely emplaced anchor is obtained by using the device of that patent application, it is necessary to form a groove which extends essentially parallel to the surface of the bone. This is a more time consuming task than simply drilling a borehole. The Noblitt et al. device requires the manipulation of the sutures to emplace it, which may result in an unreliable emplacement, and furthermore, requires a complex manipulation. The Johnson reference requires a first tool for the formation of a specialized groove which extends both essentially parallel to the surface of the bone and distally into the bone and a another tool to form the undercut for the anchor. Accordingly, the Johnson device and method is unnecessarily complex.
There is a need in the medical art for an anchor which can be emplaced simply and which is securely fastened into the bone.
There is a need also for a tool for installing such an anchor with simple motions, and preferably one simple motion.
There is a need particularly for such an anchor which can be inserted into a simple longitudinally extending borehole, i.e., a drilled borehole, and which does not require complex, time consuming-to-make grooves or other specialized manipulations.
There is a need for an anchor which can be inserted into a borehole substantially in alignment with the borehole and once inserted, activated so that it engages with the walls of the borehole by moving to a position substantially perpendicular to the borehole.
Such an anchor would be suitable, for example, to repair rotator cuff and other ligament injuries such that the appropriate attachment strength is provided.